QVC 78-4502 Manual

A SERVICE OF

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Figuring the Magnification

To figure the magnification you must first know the focal length of your telescope. Many

times the focal length will be 700mm to 900mm. Here is the formula to figure the

magnification.

Focal Length in mm

Magnification = X Barlow Lens (ie 2X or 3X)

Eyepiece in mm

3X

E

y

e

p

iece

Barlow Lens

Focusing

Tube on the

telescope.

E

y

e

p

iece

Focusing

Tube on the

telescope.

Assuming the

eyepiece is 20mm

and the focal length

is 900mm, here are

the magnifications

of each set up.

45 Power

135 Power

900÷20 = 45

(900÷20)X3=135)

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